U.S. patent number 6,554,842 [Application Number 09/803,308] was granted by the patent office on 2003-04-29 for small diameter snare.
This patent grant is currently assigned to Radius Medical Technologies, Inc.. Invention is credited to Richard M. DeMello, Richard R. Heuser.
United States Patent |
6,554,842 |
Heuser , et al. |
April 29, 2003 |
Small diameter snare
Abstract
A small-diameter surgical snare device that is capable of
fitting through existing balloon or guiding catheters includes
metal tubing along a section of a core wire. The distal end of the
core wire connects to one or more snare wires that form the snaring
loop. The distal end of the snaring loop supports a radiopaque coil
or collar that makes the end of the loop visible under fluoroscopy.
The snaring loop may consist of one or two wires or an overlap of a
tapered end of the core wire. A radiopaque coil is attached to a
distal end of the metal tubing, to provide flexibility and
visibility to a distal region of the device. Alternatively, a
polyimide tube and a short radiopaque marker may be included at a
distal end of the metal tubing. The polyimide tube fits inside of
the metal tubing, to add strength and torsion control to the distal
region of the device, while the radiopaque marker adds visibility.
In all embodiments, a shrink tube is fit over the radiopaque coil
or marker that is supported by the distal end of the metal tubing,
to ensure that the coil does not stretch when the snaring loop is
extended during use.
Inventors: |
Heuser; Richard R. (Phoenix,
AZ), DeMello; Richard M. (Acton, MA) |
Assignee: |
Radius Medical Technologies,
Inc. (Acton, MA)
|
Family
ID: |
22692938 |
Appl.
No.: |
09/803,308 |
Filed: |
March 9, 2001 |
Current U.S.
Class: |
606/108;
606/113 |
Current CPC
Class: |
A61B
17/221 (20130101); A61B 17/32056 (20130101); A61B
2017/2212 (20130101); A61B 90/39 (20160201); A61B
2090/3954 (20160201) |
Current International
Class: |
A61B
17/32 (20060101); A61B 17/22 (20060101); A61B
19/00 (20060101); A61F 011/00 () |
Field of
Search: |
;606/113,127,114,200,159,108 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
9412370 |
|
Dec 1995 |
|
DE |
|
WO 99/44524 |
|
Sep 1999 |
|
WO |
|
WO 99/51149 |
|
Oct 1999 |
|
WO |
|
Primary Examiner: Calvert; John J.
Assistant Examiner: Hoey; Alissa L.
Attorney, Agent or Firm: Cesari and McKenna, LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims priority from U.S. Provisional Patent
Application Ser. No. 60/188,390 entitled SMALL DIAMETER SNARE filed
Mar. 10, 2000.
Claims
What is claimed is:
1. A surgical snare device for ensnaring objects in the vascular
system, the snare including: A. a core wire with a proximal end and
a distal end; B. tubing that extends over the core wire, the tubing
including a metal section, the tubing having an outer diameter
sized and arranged to allow the tubing to fit through a guiding or
balloon catheter that is inserted into a blood vessel; C. a loop
with a distal end and a proximal end, the loop including two snare
wires that each attach at a respective distal end to one another
and that each attach at a respective proximal end to the core wire;
D. a first radiopaque marker that attaches to the distal end of the
loop; and E. a handle that attaches to the proximal end of the core
wire, the handle being pushed in the direction of the distal end of
the device to push the loop out of a distal end of the tubing and
being pulled in the opposite direction to pull all or a portion of
the loop into the distal end of the tubing, and wherein each of the
snare wires is constructed and arranged to spring away from one
another to define the loop when each of the snare wires are pushed
out of the distal end of the tubing and the snare wires are
constructed and arranged to move toward each other as the snare
wires are moved into the distal end of the tubing.
2. The snare device of claim 1 wherein the metal section of the
tubing extends the length of the tubing and the tubing further
includes a thin-walled inner tube that is positioned inside the
distal end of the metal section.
3. The snare device of claim 2 wherein the inner tube is made of
polyimide.
4. The snare device of claim 1 wherein the loop is spiral
shaped.
5. The snare device of claim 1 wherein the first radiopaque marker
is a collar that supports the joining of the distal ends of the
snare wires.
6. The snare device of claim 5 further including a second
radiopaque marker at the distal end of the tubing.
7. The snare device of claim 6 wherein the second radiopaque marker
is a coil.
8. The snare device of claim 7 wherein the tubing includes a shrink
tube that fits over the second radiopaque marker.
9. The snare device of claim 8 wherein the loop is spiral
shaped.
10. The snare device of claim 1 wherein the loop is oval
shaped.
11. The snare device of claim 1 wherein the loop is shaped with a
plurality of planar bends.
12. The snare device of claim 1 wherein the loop includes a
magnetic distal end.
13. The snare device of claim 1 wherein the loop is at an angle
relative to the core wire when the loop is extended beyond the
distal end of the tubing.
14. The snare device as set forth in claim 1 wherein each of the
snare wires includes a half-round or D-shaped cross section and are
stacked with respect to one another to form a
predetermined-diameter round cross section.
15. The snare device of claim 1 wherein outer diameter of the
tubing is 0.38 inch or less.
16. The snare device of claim 1 wherein the snare wires are
constructed of a superelastic alloy.
17. A surgical snare device for ensnaring objects in the vascular
system, the snare including: A. a core wire with a proximal end and
a distal end; B. tubing that extends over the core wire, the tubing
including a metal outer section and a polymer inner section, the
inner section being positioned at a distal end of the tubing, and
the tubing having an outer diameter sized and arranged to allow the
tubing to fit through a guiding or balloon catheter that is
inserted into a blood vessel; C. a loop with a distal end and a
proximal end, the loop including two snare wires that each attach
at a respective distal end to one another and that each attach at a
respective proximal end to the core wire; D. a radiopaque marker
that attaches to the distal end of the loop; and E. a handle that
attaches to the proximal end of the core wire, the handle being
pushed in the direction of the distal end of the device to push the
loop out of a distal end of the tubing and being pulled in an
opposite direction to pull all or a portion of the loop into the
distal end of the tubing, and wherein each of the snare wires is
constructed and arranged to spring away from one another to define
the loop when each of the snare wires are pushed out of the distal
end of the tubing and the snare wires are constructed and arranged
to move toward each other as the snare wires are moved into the
distal end of the tubing.
18. The snare device of claim 17 further including at the distal
end of the tubing a radiopaque marker.
19. The snare device of claim 18 wherein the marker is a coil.
20. The snare device of claim 19 wherein the tubing includes a
shrink tube that fits over the marker.
21. The snare device of claim 20 wherein the loop is spiral
shaped.
22. The snare device of claim 17 wherein the loop is spiral
shaped.
23. The snare device of claim 17 wherein the loop is oval
shaped.
24. The snare device of claim 17 wherein the loop is shaped with a
plurality of planar bends.
25. The snare device of claim 17 wherein the loop includes a
magnetic distal end.
26. The snare device of claim 17 wherein the loop is at an angle
relative to the core wire when the loop is extended beyond the
distal end of the tubing.
27. The snare device of claim 17 wherein each of the snare wires
includes a half-round or D-shaped cross section and are stacked
with respect to one another to form a predetermined-diameter round
cross section.
28. The snare device of claim 17 wherein outer diameter of the
tubing is 0.38 inch or less.
29. The snare device of claim 17 wherein the snare wires are
constructed of a superelastic alloy.
30. The snare device of claim 17 wherein the polymer inner section
comprises a polyimide inner section.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to surgical snares and more
particularly to devices for retrieving broken, dislodged, or
separated medical devices from within the vascular system.
2. Background Information
Certain snare devices have become available over recent years for
retrieving malfunctioning or misplaced devices within the
cardiovascular and non-vascular regions of the body. These
typically consist of fairly large diameter sheaths, which house a
movable central wire or wires whose distal ends are formed into a
loop or loops. The loop is used to ensnare and capture the desired
object for withdrawal and removal from the body. In use, the snare
is typically passed through a guiding catheter or other introducing
catheter that is placed within the vasculature and is directed to
the vessel or area where the misplaced or malfunctioning device is
located. The snare can then capture the intended device and
retrieve it out of the body through the introducing catheter or by
withdrawing both the snare and the introducing catheter in
tandem.
Currently available snares are designed using large diameter outer
sheaths that require larger entry sites. This may result in
complications such as excessive bleeding and/or hematomas.
Additionally, because of the large diameter of the snare, it may be
necessary to remove the existing catheters and exchange to larger
introducing devices, which increases the overall time and cost of
the procedure. A third disadvantage of the prior snares is that the
outer sheath is typically made of a plastic material that exhibits
little or no torque control, which makes ensnaring the misplaced or
malfunctioned device difficult. Lastly, the prior snares are stiff
and typically have sharp distal leading edges, which may damage
vessel walls when the device is advanced into small diameter
vessels such as those in the coronary and cerebral vasculature.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a
snare that uses a relatively small diameter outer sheath that
requires only a small entry site. Another object of the present
invention is to provide a small diameter snare that does not
require the removal of an existing catheter or exchange to other
larger devices. A third object of the present invention is to
provide a small diameter snare that exhibits superior torque
control, to simplify ensnaring a misplaced or malfunctioned
device.
To achieve the foregoing and other objects an improved snare is
provided, having a diameter of 0.39" or less, that is capable of
fitting through existing balloon or guiding catheters. The body of
the snare includes metal tubing, which allows for a very thin wall
thickness while providing stiffness for torque control and
pushability. Additionally, a radiopaque coil may be attached to a
distal end of the snare, to provide both visibility and a soft
atraumatic leading edge.
Alternatively, or in addition, the snare employs a "D" shaped snare
wire or wires to form the snare loop. This allows the wires to have
a maximum cross sectional area within the confines of the inner
diameter of the tubing, and thus, provides greater strength to the
snare loop.
The snare may be further constructed with proximal end that is
shaped to allow an extension to be added to the snare and thus
enable catheters to be exchanged directly over the snare.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention description below refers to the accompanying
drawings, of which:
FIG. 1 is a highly schematic, cut-away diagram of one embodiment of
a snare system according to the present invention;
FIG. 2 is a highly schematic, cut-away diagram of another
embodiment of a snare system according to the present
invention;
FIG. 3 is a highly schematic, cut-away diagram of a third
embodiment of a snare system according to the present
invention;
FIG. 4 illustrates a particular embodiment of the snare of FIG.
3;
FIG. 5 is a diagram of a fifth embodiment of a snare system
according to the present invention deployed in a catheter within an
artery;
FIG. 6 is a diagram of the snare of FIG. 5 with a magnetic tip;
FIGS. 7-10 are partial cut-away diagrams of the snare of FIG. 5
with various shapes of snare loop; and.
FIGS. 11 and 12 are highly schematic, cut away diagrams of a sixth
embodiment of a snare system according to the present
invention.
Although the following Detailed Description will proceed upon
reference being made to specific embodiments and methods of use, it
should be appreciated that many alternatives, variations, and
modifications thereof are possible without departing from the
present invention. Accordingly, it is intended that the present
invention be viewed broadly as encompassing all such alternatives,
variations, and modifications.
DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT
Referring now to FIG. 1, a small diameter snare device 10 includes
a hollow elongated stainless steel tube 12 through which a core
wire 14 extends to support a snare loop 16. A distal end 22 of the
tube supports a radiopaque coil 24, which provides visibility to
the end of the tube under fluoroscopy. The coil also provides
flexibility to the distal region of the device. A teflon shrink
tube 26 fits over the coil and serves to prevent the coil from
stretching when the snare loop is extended, as discussed below. As
depicted in the drawing, a second radiopaque coil 25 may be
attached to a distal end 28 of the snare loop 16, to provide
visibility to the end of the loop under fluoroscopy. Further, an
atraumatic tip 30 may be attached.
The snare loop 16 is formed from first and second snare wires 32
and 34, which are shaped to spring into a loop when the wires are
pushed out of a distal end of the tube 12 and/or coil 24, as
discussed below. The diameter of the snare wires is approximately
50% the diameter of the mid-section of the core wire, such that the
snare device has an essentially uniform cross-section over its
length. The snare wires may each have a D-shaped cross-section, to
maximize the cross-sectional area and still fit within the inner
diameter of the tube, as discussed in more detail below.
The wire 32 attaches at a proximal end 36 to a distal end 15 of the
core wire 14, by brazing, soldering or other attachment mechanisms.
A collar 38 supports the joint between the core and the first snare
wire. A distal end 37 of the first wire supports the distal
radiopaque coil 25 and the tip 30. As depicted in the drawing, the
core wire may taper at the distal end, to accommodate the collar 38
and also to provide flexibility to the distal end of the device 10.
Similarly, the distal end of the first snare wire may be tapered to
provide greater flexibility.
The second snare wire 34 attaches to the first snare wire 32 at a
proximal end 40 and a distal end 42 by brazing, soldering or the
like. As shown, a collar 44 may support the joint at the distal end
of the second wire.
A proximal end 46 of the core wire 14 supports a handle 48. The
handle is used to control the positioning and orientation of the
snare loop 16. When the handle is in a first position, as shown in
the drawing, as the snare device is introduced into the body
through a catheter 90 (FIG. 5). The snare loop 16 is thus pulled
back inside the tube 12 and/or the coil 24. When the snare device
is in place in the body, with the distal end of the device end
adjacent to an object (not shown) that is to be removed from the
body, the user pushes the handle in the direction of the distal
end, to push the snare loop out of the end of the tube and/or coil.
The snare wires 32 and 34 then spread into a shape for en-snaring
the desired object. The snare wires may spread to shapes similar to
those shown in FIGS. 2-11.
Once the snare loop 16 has ensnared the desired object, the user
may pull on the handle 48, to draw the snare loop 16 slightly back
into the tube 12 and/or coil 24 until the loop tightens around the
object. The snare device 10 and, as appropriate, an introducing
catheter, are then withdrawn from the body, to withdraw the
ensnared object.
Referring now to FIG. 2, the device may include a second stainless
steel tube 50 that fits inside the tube 12. In this embodiment, a
first snare wire 52 extends through the inner tube and the handle
48 (FIG. 1) attaches to a proximal end 56 of the first snare wire.
The second snare wire 54 extends along a portion of the first snare
wire and attaches at a proximal end 60 to the first snare wire by
brazing, welding, soldering or the like. The distal end 58 of the
first snare wire similarly attaches to the second snare wire. The
distal end 62 of the second snare wire extends beyond the distal
end of the first snare wire and supports a relatively short
radiopaque coil 64 and the atraumatic tip 30. The coil 64 is
approximately 1 mm in length. As shown, a collar 66 may support the
joint at the distal end 17 of the loop 16.
Referring now to FIGS. 3 and 4, the snare loop 16 may be formed
from one or more shaped snare wires 70 that attach at proximal ends
74 and 76 to a tapered end distal end 15 of the core wire 14. A
ribbon wire 78 extends from the proximal end 22 of the tube 12 to a
proximal end 23 of the coil 24, and the coil and snare wires attach
also to the ribbon wire. The distal end 17 of the loop 16 may be
pinched a shown in FIG. 11, to support the second radiopaque coil
25 and the atraumatic tip 30 (FIG. 2). FIG. 4 depicts the loop 16
shaped to extend at an angle relative to the core wire 14. The
proximal end 80 of the core wire 14 is shaped to allow extensions
(not shown) to be fit onto the end of the snare device.
FIG. 5 depicts the snare device 10 in place in a catheter 90 that
is introduced into an artery 92. As shown, the snare device may
have a spiral shaped loop 16 that expands essentially to the full
diameter of the artery. FIG. 6 depicts the device of FIG. 5 with a
magnetic tip 94 attached to the distal end of the loop. The
magnetic tip, which is included to attract metal objects (not
shown) into the loop, may be various shapes. FIGS. 7-10 depict the
snare device 10 with various shaped loops 16, with FIG. 10 showing
the loop including multiple planar bends or fingers 82. The distal
ends 17 of the various shaped loops 16 of FIGS. 5-10 may be
pinched, as discussed above, to support the second radiopaque coil
25 and tip 30 (FIG. 2).
FIG. 11 depicts the snare device 10 with a thin-walled polyimide
tube 100 fit into the distal end 22 of the metal tube 12. The
polyimide tube, which has a high burst strength and is relatively
stiff, provides torque control to the end of the device. A
radiopaque marker 102 is positioned at the distal end of the
polyimide tube and the shrink tube 26 is positioned over the marker
and shrunk to hold the marker in place. The marker may be a 1 cm
long radiopaque coil with a 0.020" outer diameter that is wound
with 0.004".times.0.012" wire. The snare loop 16, which is spiral
shaped, is formed from two snare wires 104 and 106 that attach to
one another at their distal ends 108 and to one another and to the
core wire 14 at their proximal ends 110. A radiopaque collar 112
supports the joint at the distal ends of the wires and provides
visibility. The collar may also support the is atraumatic tip 30
(FIG. 1). As depicted in the drawing, the proximal end 46 of the
core wire 14 supports the handle 48. FIG. 12 depicts the device of
FIG. 11 with a proximal end 114 that is shaped to allow an
extension to slideably connect to the device.
In all embodiments, coatings can be applied to the core wire and/or
to the outer surfaces of the tubing, to reduce friction between the
core and the tube as well as to enhance movement of the snare
device within a catheter.
The entire device when complete can be made less than 0.014" in
diameter and is capable of being placed directly through a PTCA
balloon catheter or other small diameter catheter that may already
be in place within the patient. Alternatively, the snare may be
passed through the guiding catheter along side of the balloon or
access catheter without the need to remove the prior device and
thus lose temporary access to the site within the patient.
As discussed previously, the snare wire or wires may have a half
round or "D" shaped profile, to maximize the cross sectional area
of the wire and thereby increase its overall breaking strength
(see, for example, cross section CS in FIG. 2). For example, a tube
with a 0.008" inner diameter can accommodate two 0.004" diameter
round wires stacked together or the equivalent of a single 0.008"
diameter wire if two "D" shaped wires are stacked. The total cross
sectional area of a 0.004" diameter wire is 0.000013 sq. in.
whereas the "D" shaped wire has a cross sectional area of a
0.000025 sq. in. Using the D-shape wire thus results in a doubling
of the cross-sectional area and a likewise doubling of the breaking
strength of the wire.
As also discussed, the proximal end of the core wire 14 and
actuating handle 48 may be shaped such that an additional length or
wire can be attached to the device, thereby extending the overall
length of the device. This, in turn, allows one catheter to be
exchanged for another catheter over the body of the snare. For
example, the snare may be initially passed through a PTCA balloon
catheter, which is already located within the target area. The
balloon catheter can then be removed and replaced with a catheter
that has a larger inner diameter, that may allow the snare and the
ensnared object to be removed through the catheter.
Any combination of the tubing, central core, or snaring loop may be
fabricated from a superelastic alloy such as Nitinol, to enhance
the torquability or kink resistance of the device. Additionally,
the snaring loop can be made as an integral part of the central
core by reducing the diameter of the end of the central core and
doubling this end over to form the loop. The terminal end of the
core can then be attached to a more proximal section of the
reduced-diameter core at a location at the base of the formed loop.
As discussed, the distal end of the loop formed in the core wire
may be pinched to form the distal end 17 that supports a radiopaque
collar or other shaped marker.
Dimensional ranges contemplated for the above embodiments of the
present invention include lengths of between 20 cm and 500 cm,
diameters between 0.010" to 0.039" and loop diameters between 1 mm
and 20 mm.
* * * * *